New files for ValueListEditor Strings property editor.

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@44574 4005530d-fff6-0310-9dd1-cebe43e6787f
IdeIntf: Property editor for Strings in ValueListEditor. Does not work well yet.

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@44575 4005530d-fff6-0310-9dd1-cebe43e6787f